1. Field of the Invention
The present invention relates to a case for installing a light-emitting semiconductor element for use in LED etc. formed from a white thermosetting silicone resin composition and a cured material of its composition for a light-emitting semiconductor device, especially the case for installing a light-emitting semiconductor element wherein the resin composition and the cured material have a low light transmittance rate, an excellent moldability and are difficult to cause a burr to occur in molding.
2. Description of the Related Art
A light-emitting semiconductor element such as a LED (Light Emitting Diode) has been widely used as each of various kinds of indicators or light sources for a street display, an automobile lamp, or a residential illumination. Currently, a polyphthalamide resin (PPA) has been widely used as one of the materials of semiconductor devices and electronic devices.
However, there is a problem that light output decrease etc. occurs by yellow discoloration etc., resulting from long-term use of semiconductor element sealing and case using conventional PPA resin materials as colorless or white materials especially. This is because light wavelength is shorter and light energy is higher in order to increment the power and improve the color rendering properties of a light-emitting semiconductor element for increasing in brightness, in recent years.
Additionally, in regards to the details, Patent Document 1 has disclosed a light-emitting semiconductor device consisting of a B-stage epoxy resin composition for sealing light-emitting semiconductor wherein a sealing resin has constituents of an epoxy resin, a curing agent and a hardening accelerator, and a cured material of resin composition which said constituents have been uniformly melted at the molecular level. In this case, a bisphenol A epoxy resin or a bisphenol F epoxy resin is mainly used as an epoxy resin, and it has been disclosed that triglycidyl isocyanurate etc. can also be used. However, the triglycidyl isocyanurate was only used by adding in small amounts to a bisphenol epoxy resin in Examples. And, according to the result of the study by the inventors of the present invention, this B-stage epoxy resin composition for sealing light-emitting semiconductor has a problem that it turns yellow by being left especially for a long time at a high temperature.
Furthermore, Patent Documents 2 to 4 have disclosed use of triazine derivative epoxy resin in an epoxy resin composition for sealing light-emitting element, whereas a problem that it turns yellow by being left for a long time at a high temperature is substantially unresolved in any case.
Moreover, Patent Document 5 has disclosed a resin composition for reflecting light whose light reflectivity in light wavelength of 350 to 800 nm is higher than or equal to 70%. However, since the composition is the epoxy resin composition, it has a potential problem of exhibiting yellow discoloration when it is used for a long time at a high temperature, or when the LED is a high brightness type such as UV LED, white LED and blue LED.
Additionally, Patent Document 6 has disclosed a resin composition for sealing LED containing an organopolysiloxane having a weight-average molecular weight of higher than or equal to 5×103 and a condensation catalyst. However, it is unsuitable for a transfer molding or a compression molding because this organopolysiloxane has to have transparency and be in the form of a liquid at ambient temperature.
Furthermore, Patent Document 7 has disclosed a transfer moldable resin composition for reflector of LED containing an inorganic filler and a condensation catalyst wherein the inorganic filler consists of a silanol group-containing organopolysiloxane, a straight-chain diorganopolysiloxane residue-containing organopolysiloxane, a white pigment and a silica. It can easily cause transmission of light and occurrence of a burr in molding because its refractive index is close to that of silanol group-containing organopolysiloxane and the silica.